I am building a motor with a racing beat streetport and a 35r t4 1.06 hotside with a goal of approx 425 to 450 hp. Ive seen a few dyno plots with torque ranging from 330 to 390ish. I'm trying to find the most streetable clutch for my setup and I'm stuck between the act xtss (450 tq) or the hdss (400 tq). I'd like to go with the hd pressure plate due to the decreased pedal effort compared to the xt but I don't want to get it and have it slip either. This is mainly going to be a street car with some 1/4 mile activity, what do you guys think ?

 

ACT extreme duty feels pretty good here.

 

Spec has more choices for the FD.

http://www.specclutch.com/

 

I've had bad luck with Spec reliability.

 

both those ACT torque numbers are at the flywheel. so 450 becomes 380 and 400 is 340.

the problem w the rotary clutch is the engine is so compact that the flywheel is small in relation to turboed output. since we have less frictional area we need to either go up on the spring rate/clamp force or run a multiple disc so as to increase frictional area.

going up on the spring rate creates high pedal pressure and stresses the clutch actuating fork.

going up on the frictional area is expensive. $1475 for the right stuff. but you are, then, able to run comfortable spring pressure.

i ran the exedy hyper single until i outgrew it torquewise. IMO, it is the best single but will not hold 20 psi of boost. i now run the exedy twin cerametallic and love everything about it other than the cost.

that all said, there are many getting along w some sort of ACT combos.

clutch packages are perhaps the most difficult balancing act (no pun intended) w the FD. take a look at the size of the frictional area on an LS1 for instance. huge. so they get along w comfortable spring pressure.

hc

 

Thanks for the info Howard, I've heard the twin plate clutches are very noisy. Is there any truth to that? I would like the car to be bearable for street use.

 

For street use you will need the ACT extreme pressure plate and the HD organic disk at the minimum.

I had the HD pressure plate and HD organic disk on my FC and it started to slip once I got some tires that hooked up a bit.

I went with copper sprung 6 puck and kept the HD pressure plate DESPITE ACT's recommendation since I feared the extreme duty PP reliability. My set up works great, but most people would hate it for the street and it still slips if I try a 2nd gear launch to avoid wheelspin.

BTW the sound of a multiplate clutch rattling away in neutral is one of the coolest noises this side of idle lope for car guys- who cares if everyone else thinks your car is broken/needs a tune up.

 

bump.. for good question as I have been doing research in this aspect as well. more info!! Thanks

 

Hey, would the Exedy twin plate carbon clutch be quiet since there is no metal on metal?

Or is the ringy ring ding just replaced with clunky clunk thunk?

 

i can't directly comment on carbon as after examining all the aspects of carbon i elected cerametallic.

i put approx 5000 miles on my exedy twin cerametallic and am very pleased. it has comfortable pedal pressure. since the frictional area is doubled exedy was able to back off on pedal pressure. i believe my exedy hyper single cerametallic was 2600 pounds spring pressure and the double is 2200.

as to rattle.... there is almost none. it is not an issue and only does happen in neutral with your foot off the pedal. maybe it can be heard outside the car. maybe not.

the clutch is able to be slipped a bit in normal driving.

as to cerametallic V carbon. carbon's coefficient of friction is between .28 and .48 depending on heat. cerametallic is .49 and is not heat effected. there's lots of talk about having to slip the carbon clutch a bit before asking it for full grip. i have no experience here so will not comment other than to point out the difference in friction in re to heat.

tilton makes a real carbon carbon clutch in that the slider plates are also carbon. most other carbon clutches are really carbon/steel in that the floater plates are steel. that's what causes the primary frictional/heat related issue.

the problem is the Tilton package is around 2X the exedy carbon/steel which is expensive in itself.

finally, the "cerametallic" material that exedy uses is patented. not all cermetallics are the same. i put between 5 and 10,000 miles on my Exedy Hyper Single and the thickness of the disc was 4.58 MM V new at 4.6!

i consider both the single and double to be street friendly.

hc